Moon Middle

There's a couple of cool things in here. The skip-crater Messier A and B on the right and, just left of center, the identical double craters Ritter and Sabine, probably made by the impact of a double asteroid. Apollo 11 is near the middle of the frame.

1/10 sec, ISO 200, T2i, Barlow through a 4" refractor to give 3000 mm. Stack of four images.

I actually desaturated it a bit. Otherwise, levels and some sharpening. I found that you can remove some of the more obvious sharpening signs by using various dust and scratch filters.

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That is just an awsome shot for a 4" refractor.Which scope are you using?

It's just this little guy. Not a big scope by any means and, at Barlowed up to 3000 mm EFL, it's pushed to its optical limits:

http://www.telescope.c​om …ope-optical-tube-assembly

Really nice! Do moon shots like this require a tracking mount? 1/10 seems fast enough that a standard tripod would do, but with all of the magnification, I don't know...

Thanks!
-Raj

Bernoulli , GREAT SHOT !! Refractors produce the sharpest images of telescopes and thats a fact ! WTG !

Hi Ron, haven't seen you for a while! You just can't beat those refractors for sharpness. Kind of like an L lens without the variable aperture.

Senevirante - The short answer is that at this really high magnifcation (3000 mm) you just barely start to need a driven mount. The moon moves its diameter every 2 minutes and, while that doesn't seem like much, if you shoot above about 1000 mm or so you might start to get some smear.

Now let's get more technical: the Moon moves 15 arc seconds per second so, at 1/10 sec, it would move 1.5 arc seconds. On the Moon, 1 arc second is 1.9 km. There is a tiny crater right near the middle of the frame that is 2.4 km in diameter (Collins) and I can just make it out. So something that small would be very slightly smeared.

But you never need a tracking mount with a lens under 1000 mm. The only reason then is convenience so you can keep the Moon in the frame long enough to focus and shoot.